Here I am

'08 6.7L Starting

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Stumble at 38-45 mph

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Hey there!



My '93 would fire up as soon as the engine turned over. In my '08 It seems that I need to crank it over several times before it catches! Is this "normal" or is there an underlying issue that I need to get addressed? Fuel Pump? Lift Pump?



Any thoughts folks!
 
Mine is the same way. I've attributed it to ECM needing to take various readings from its various sensors to get itself all straightened out before delivering fuel.
 
My '04. 5 cranked longer than I thought it should, but it was my first diesel so I didn't worry about it. My 2008 cranks longer than the '04. 5 did, but I guess that's the way they are. Had 80,000 miles on the '04. 5 and now have 15,000 on the 2008, with no problems, so I guess it's just the way they are.
 
We have several trucks... . our new 08 5500 takes about 2x's as long to start... . seems like it cranks forever... I can only assume that the computer is gathering information needed for a better start based on what the sensors are seeing... . so that when it starts it starts cleaner... .
 
Hope I have this right. If not, someone smarter than me will correct me.



On the pre-common rail engines, the injection timing was determined mechanically by the position of the cam. The common rail engines use a crank position sensor to determine when to fire the injectors, so the crank has to rotate far enough for the sensor to determine the position.
 
Hope I have this right. If not, someone smarter than me will correct me.



On the pre-common rail engines, the injection timing was determined mechanically by the position of the cam. The common rail engines use a crank position sensor to determine when to fire the injectors, so the crank has to rotate far enough for the sensor to determine the position.



Close... ... ... . the position of the inj pump in relation to cam position and it's internal timing





Bob
 
Starting

I agree my 96 started by barely touching the starter. The 07 takes several turn overs. But then what a difference, more hp more tourqe better everything else,love the new ride. 15000 mi. and no problems so far.
 
I haven't noticed that the truck actually cranks longer than my 2000 truck, but it does crank longer than my 1995 truck.



I have, however, noticed that the 2008 truck needs a second or two to think about starting after I turn the key to "Start. " It doesn't actually crank the engine immediately. With every other vehicle I've ever driven, the key is directly linked to the starter. The 2008 truck key seems to be talking to a computer that will decide when it wants to start the truck.



I find that delay to be a bit of an annoyance.



Loren
 
Loren, I haven't noticed any delay in mine, it seems to crank immediately. My 95 used to start in half a revolution, the 08 takes 4.
 
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Could it have to do with needing to see oil pressure before it will deliver fuel? My old 01 would fire if I just bumped the starter, then take a few seconds for oil pressure. The 08 "seems" to have oil pressure more quickly.



I remember reading somewhere that the International engines in the Ford's wanted to see oil pressure before it would fuel. They seemed to crank forever also.



I have no idea, just wondering aloud.



Chris
 
The instant starts are on the mechanical injected trucks. The newer ones with electronic injection take longer for lots of reasons. Just like fuel injected cars. Whole differant system.
 
The old powerstrokes had a fuel pump that was driven by oil pressure so they needed oil pressure for fuel pressure. I don't know about the new ones though.
 
I'm curious, what is considered a long cranking time, time wise? Also, remember that the starter may sound like it's spinning fast, but there's alot of gear reduction and the crankshaft is'nt really rotating as much as the "cranking" sound seems to indicate. My 6. 7 starts quick enough not to consider it an issue, and is comparable to the VP44 5. 9's I've had.
 
I'm curious, what is considered a long cranking time, time wise? Also, remember that the starter may sound like it's spinning fast, but there's alot of gear reduction and the crankshaft is'nt really rotating as much as the "cranking" sound seems to indicate. My 6. 7 starts quick enough not to consider it an issue, and is comparable to the VP44 5. 9's I've had.



Well, my 95 would start in half a revolution when warm, the 6. 7 still starts fast IMO, usually on revolution #3 and always by the start of the 4th revolution. Sometimes it starts on the second one but usually not. Doesn't bother me in the least.
 
I have noticed the same, However I have a routeine that I do for starting now, I get in the ruck, put the key in the ignition, turn it to run, Then stop, put my seat belt on, then go back and turn the key to start.



While the cranking time is longer then my 12 valve I noticed by doing this that the cranking is shorter. I also will see my fuel pressure build before I attempt a start by doing this.



And when its cold it just means a slightly shorter time waiting for the grid heater to warm up.
 
Loren, I haven't noticed any delay in mine, it seems to crank immediately. My 95 used to start in half a revolution, the 08 takes 4.



Coalsmoke,



Thanks for the information. I'll discuss it with my dealer the next time I see them. I want to be sure to get this documented in case it's a problem.



Loren
 
I have noticed the same, However I have a routeine that I do for starting now, I get in the ruck, put the key in the ignition, turn it to run, Then stop, put my seat belt on, then go back and turn the key to start.



BBjorn,



I'm going to try your method and see if the truck cranks sooner. Maybe it needs to go through a POST before it cranks.



(For non-geeks: POST = Power On Self Test. That's what your computer is doing for those 15 minutes while it boots. )



Loren
 
If you watch the engine, what you hear as "revolutions" are usually only a single cylinder going through the compression stroke... .



If you think about it that way, the cranking time seems much shorter.



Merrick
 
If you watch the engine, what you hear as "revolutions" are usually only a single cylinder going through the compression stroke... .



If you think about it that way, the cranking time seems much shorter.



Merrick



How did you come to this conclusion? I just had Fiancee start the truck a few times with me watching and it sure looked like full revolutions to me, but granted it was a little hard to tell without putting a tach on it.



On a side note, these fan blades are incredibly sharp, don't ask how I know:rolleyes:
 
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